Another coincidence? This post brings up some interesting points.
How it relates to my POI: from what I see and take from this is My POI’s exwife took his daughter and would not tell him where they were. Her name was Cheri. In 1969, the cab driver was shot and the Zodiac Killer was seen walking up Cherry Street after exiting the cab. In his letter he says he was the one who shot the cab driver on Washington and Maple. Cherry was missing. The name Cheri was found hidden in corner of the z340 cipher letter a month later. The z340 is said to contain the Zodiac Killers identity.
Cheri (Cherry) was missing.
I believe none of the ciphers have ever been correctly solved. I dont believe he actually put his name in the codes. I think he put clues or pieces to a puzzle that if found would lead you to general references of popular stories that he was writing in to the media about during that time. Which would have eventually led law enforcement to him.